1. Field of the Invention
This invention relates to a pluggable coupling for connecting pressure lines carrying compressible as well as incompressible fluids, comprising a female coupling connector and a male coupling connector.
2. Description of Prior Art
Conventional linear couplings for pressure lines have, in general, a male coupling connector and a female coupling connector, a locking mechanism which keeps the female connector and the male connector together, and a blocking device which prevents fluid under pressure from flowing out or escaping when the coupling is disconnected. To make a connection, in most conventional couplings, the male coupling connector is inserted into the female coupling connector and the male connector is fixed in the female connector by a locking system. When the male coupling connector is inserted into the female connector, the blocking device of the coupling is opened and the fluid is allowed to flow through the coupling. If the coupling is disconnected, the flow is interrupted again. Accordingly, it is necessary, during coupling and locking as well as when disconnecting such a coupling, to push the male connector in the direction of the female connector. The force necessary for this depends on the pressure in the pressure line and the effective cross-sectional surface of the coupling. The effective cross-sectional surface consists of the inner cross-sectional surface of the male connector or the female connector and of the annular cross-sectional surface of the male connector or the female connector on which the fluid under pressure acts when the blocking device of the coupling is opened. With high pressure, a large expenditure of force is required to insert the male connector into the female connector and to lock it or, in the locked position, to remove the male coupling connector from the female coupling connector. In most cases, the coupling or uncoupling operation cannot be performed with one hand because of the large expenditure of force required and because it is necessary to press the male coupling connector against the female coupling connector and simultaneously operate the locking mechanism.
In contrast to conventional linear couplings, conventional pivotable couplings use a pivotable blocking member as a female coupling connector which also blocks the flow in the uncoupled state. The male coupling connector is inserted without any pressure forces acting on it at an oblique angle to the pressure line into the blocking member which is pivotably seated in a coupling housing. The pressure line is still interrupted after this insertion. By pivoting the male coupling connector and the blocking member in the interior of the coupling housing, the coupling is straightened out to allow fluid to flow through the coupling. As soon as the male connector is straightened out, the blocking member is secured against pivoting because the male connector is pushed back in the female connector by pressure in the pressure line into a recess in the coupling housing. In this way the coupling is locked. This process of coupling and locking can take place with a relatively small amount of force because it is only necessary to overcome the frictional forces acting on the blocking member when the blocking member is pivoted. However, uncoupling requires a comparatively large amount of force. To unlock the blocking member it is first necessary to push the male connector out of the recess in the coupling housing toward the female coupling connector. The force required for this depends on the pressure in the pressure line which may be considerable. When the blocking member of the coupling is pivoted, the blocking member blocks the flow until the male coupling connector passes over a relief bore in the coupling housing. The pressure difference between the pressure in the interior of the male coupling connector to be removed and the atmosphere pressure is reduced in this pivoted position. Then the blocking member is pivoted further so that the male connector can be removed without being under pressure out of the female connector.
With both of the above mentioned types of couplings--namely the linear coupling as well as the coupling having a pivotable blocking member, the seal between the female coupling connector and the male coupling connector is positioned in the female connector and the exterior of the male connector has a sealing face, or the interior of the female connector has a sealing face and the seal is located on the exterior of the male connector. These structures are disadvantageous because the sealing face or the seal of the coupling can be easily damaged because they are outwardly facing. In actual use the male coupling connector is, in most cases, mounted on a loose hose end. If the male coupling connector is not connected, the sealing face can easily be damaged and rapidly becomes dirty. Male coupling connectors which lie on the ground unprotected are damaged, for example, by vehicles rolling over them, by dragging the hose on the ground and other effects on the sealing faces. This results in increased waste and rapid wear of the coupling parts. If the sealing face or the seal are damaged, the coupling becomes leaky and the defective coupling part must be replaced.